diff --git a/mod/forum/discuss.php b/mod/forum/discuss.php
index e33b7554f7b..09c747a4310 100644
--- a/mod/forum/discuss.php
+++ b/mod/forum/discuss.php
@@ -45,14 +45,14 @@ $discussionvault = $vaultfactory->get_discussion_vault();
 $discussion = $discussionvault->get_from_id($d);
 
 if (!$discussion) {
-    throw new \moodle_exception('Unable to find discussion with id ' . $discussionid);
+    throw new \moodle_exception('errordiscussionnotfound', 'mod_forum');
 }
 
 $forumvault = $vaultfactory->get_forum_vault();
 $forum = $forumvault->get_from_id($discussion->get_forum_id());
 
 if (!$forum) {
-    throw new \moodle_exception('Unable to find forum with id ' . $discussion->get_forum_id());
+    throw new \moodle_exception('errorforumnotfound', 'mod_forum');
 }
 
 $course = $forum->get_course_record();
diff --git a/mod/forum/lang/en/forum.php b/mod/forum/lang/en/forum.php
index fc9447665ab..ad21298a737 100644
--- a/mod/forum/lang/en/forum.php
+++ b/mod/forum/lang/en/forum.php
@@ -258,11 +258,13 @@ $string['emaildigesttype_help'] = 'The type of notification that you will receiv
 * Digest - subjects only - you will receive one digest e-mail per day containing just the subject of each forum post.
 ';
 $string['emptymessage'] = 'Something was wrong with your post. Perhaps you left it blank, or the attachment was too big. Your changes have NOT been saved.';
+$string['errorcannotlock'] = 'You do not have the permission to lock discussions.';
+$string['errordiscussionnotfound'] = 'The discussion was not found';
 $string['erroremptymessage'] = 'Post message cannot be empty';
 $string['erroremptysubject'] = 'Post subject cannot be empty.';
 $string['errorenrolmentrequired'] = 'You must be enrolled in this course to access this content';
+$string['errorforumnotfound'] = 'The forum that this discussion belongs to was not found';
 $string['errorwhiledelete'] = 'An error occurred while deleting record.';
-$string['errorcannotlock'] = 'You do not have the permission to lock discussions.';
 $string['eventassessableuploaded'] = 'Some content has been posted.';
 $string['everyonecanchoose'] = 'Everyone can choose to be subscribed';
 $string['everyonecannowchoose'] = 'Everyone can now choose to be subscribed';